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[bpf-next,v2,03/15] selftests/bpf: check if imprecise stack spills confuse infinite loop detection

Message ID 20240108205209.838365-4-maxtram95@gmail.com (mailing list archive)
State Accepted
Commit c035b3e555b5642f786fb2d089a6ddf7b00eb374
Headers show
Series Improvements for tracking scalars in the BPF verifier | expand

Commit Message

Maxim Mikityanskiy Jan. 8, 2024, 8:51 p.m. UTC 
From: Eduard Zingerman <eddyz87@gmail.com>

Verify that infinite loop detection logic separates states with
identical register states but different imprecise scalars spilled to
stack.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
---
 .../selftests/bpf/progs/verifier_loops1.c     | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)
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Patch

diff --git a/tools/testing/selftests/bpf/progs/verifier_loops1.c b/tools/testing/selftests/bpf/progs/verifier_loops1.c
index 71735dbf33d4..e07b43b78fd2 100644
--- a/tools/testing/selftests/bpf/progs/verifier_loops1.c
+++ b/tools/testing/selftests/bpf/progs/verifier_loops1.c
@@ -259,4 +259,28 @@  l0_%=:	r2 += r1;					\
 "	::: __clobber_all);
 }
 
+SEC("xdp")
+__success
+__naked void not_an_inifinite_loop(void)
+{
+	asm volatile ("					\
+	call %[bpf_get_prandom_u32];			\
+	r0 &= 0xff;					\
+	*(u64 *)(r10 - 8) = r0;				\
+	r0 = 0;						\
+loop_%=:						\
+	r0 = *(u64 *)(r10 - 8);				\
+	if r0 > 10 goto exit_%=;			\
+	r0 += 1;					\
+	*(u64 *)(r10 - 8) = r0;				\
+	r0 = 0;						\
+	goto loop_%=;					\
+exit_%=:						\
+	r0 = 0;						\
+	exit;						\
+"	:
+	: __imm(bpf_get_prandom_u32)
+	: __clobber_all);
+}
+
 char _license[] SEC("license") = "GPL";